The invention relates to a disk brake comprising a brake anchor plate which is fastenable to a vehicle, a floating frame which engages over a brake disk of the brake and is guided on the brake anchor plate, at least one brake shoe which in the installed state of the brake is supported against the floating frame at the side of the brake disk directed towards the outside of the vehicle, at least one further brake shoe which in the installed state of the brake is supported counter to braking forces against the brake anchor plate at the side of the brake disk directed towards the inside of the vehicle, and at least one operating piston which is disposed on the floating frame. The invention also relates to a brake lining for such a disk brake.
A disk brake of the type described initially is known from EP 0 412 541 B1 and EP 0 480 366 A1. In both cases, the disk brake is notable for the fact that two separate brake shoes are disposed on either side of the brake disk, and that at least one pair of operating pistons are provided, which are disposed on the floating frame symmetrically in relation to an axial centre plane of the brake anchor plate. The invention relates in particular to an improvement of said known sectional-lining disk brake in view of simple and reliable assembly of the brake shoes. The invention is however quite generally applicable to disk brakes of the type described initially.
Fastening to the floating frame of the brake shoes, which in the installed state of the brake are disposed at the side of the brake disk directed towards the outside of the vehicle, is problematical with sectional-lining disk brakes according to prior art. Particularly during hard braking operations, the fastenings of the brake shoes are subject to considerable loads. This may lead to loosening of the brake shoes. In the disk brake described in EP 0 480 366 A1, for example, the brake linings disposed in the installed state of the brake at the side of the brake disk directed towards the outside of the vehicle are supported against pins, which are pressed into bores of the floating frame. When the vehicle brake over an extended period is operated in the so-called 1 g range, i.e. operated so hard that the vehicle is braked at a deceleration of 1 g, the acceleration due to gravity of around 10 m/s2, said pins may work loose. As a result, the stability of the arrangement of the brake shoes is seriously impaired.
From DE 33 46 479 A1 a disk brake having a brake anchor plate, a floating frame, a plurality of brake shoes and an operating piston is known. A brake shoe disposed at the side directed towards the outside of the vehicle is provided at its side remote from a brake disk with projections in the form of ribs. The floating frame of the disk brake has complementary recesses in the form of grooves.
The object of the invention is therefore to provide a more secure and reliable design for the support and/or fastening of the brake shoes, which in the installed state of the brake are disposed at the side of the brake disk directed towards the outside of the veheicle. A further object of the invention is to enable simple and operationally reliable installation of the brake shoe.
Said object is achieved according to the invention by a disk brake according to claim 1 or claim 2.
The brake shoes described in claims 10 and 11 correspond to said solution according to the invention.
Preferred refinement of the invention are described in the dependent claims.
Thus, the dimensions of the brake are preferentially such that the installation of a new (replacement) brake shoe is possible only when the said projection engages into the recess or groove.
A preferred refinement of the invention provides that the two recesses are arranged in a stepped manner such that the projection during installation latches into the further recess so that the fitter may be certain that the brake shoe is situated in the correct position. In said case, the further recess preferentially takes the form of a bore. In the installed position of the brake shoe the projection engages into the bore, and indeed preferably with a precise fit so that, firstly, from the engagement of the projection into the additional recess the fitter may tell that the brake shoe is seated securely and in the correct position and, secondly, by virtue of application of the projection against the walls of the further recess the brake shoe is secured in addition to the optionally further provided support.
It is advantageous when the recess, which preferentially takes the form of a groove, in installation direction and/or the direction, in which the projection is guidable into the groove, terminates after the recess at a stop. By said means, the fitter installing the brake shoes notices at which point of the groove the further recess is situated and therefore at which moment during introduction of the brake shoe a suitable pressure of the brake shoe onto the floating frame has to be exerted in order for the projection to latch in the recess.
It is likewise advantageous when the height of the projection and the distance between the floating frame and the brake disk are such that the distance between the surface of the first brake shoe, which is directed towards the brake disk, and the brake disk during guidance of the projection in and along the groove or of the groove over the projection is smaller than the depth of the groove. It is therefore namely impossible for the brake shoe to be introduced into the space between the floating frame and the brake disk without the projection sliding along in the groove, because there is no room to guide the projection along next to the groove on the surface of the floating frame. In the first alternative, the projection is preferentially positioned in the brake shoe as far away as possible from the region of the first brake shoe which is grasped during installation of the brake shoe. This may mean, for example, that the projection is situated in the vicinity of the bottom edge of the brake shoe because the brake shoe is grasped in the region of the top edge during installation. For the sake of simplicity, the expressions xe2x80x9ctopxe2x80x9d and xe2x80x9cbottomxe2x80x9d here are taken to mean that the brake is installed with a vertically extending centre plane. In said case, the expressions xe2x80x9ctopxe2x80x9d and xe2x80x9cbottomxe2x80x9d relate to the vertical. To the person skilled in the art it is self-evident that brakes may also be installed in other ways, namely not so that their centre plane extends vertically. It goes without saying that the expressions xe2x80x9ctopxe2x80x9d and xe2x80x9cbottomxe2x80x9d for such cases are to be taken to have an analogous meaning in the sense that xe2x80x9ctopxe2x80x9d means xe2x80x9cradially outerxe2x80x9d and xe2x80x9cbottomxe2x80x9d means xe2x80x9cradially innerxe2x80x9d.
The previously described arrangement of the projection in the vicinity of the bottom edge of the brake shoe, on the one hand, has the advantage that the groove may as a result be of a particularly long design so that the brake shoe is guided in the groove virtually throughout the process of introduction into the brake. On the other hand, said feature is advantageous when the brake shoes are glued to the floating frame so as to form with the latter a coupling mass in relation to vibrations. In said case, the brake shoe is generally already provided at its side to be affixed, i.e. at the rear side, with an adhesive layer which is covered by a protective foil for transportation purposes. Immediately prior to installation of the brake shoes, the protective foil is removed to expose the adhesive layer. During introduction of the brake shoes, contact between the adhesive layer and the frame is to be avoided as far as possible up to attainment of the end position. Maximizing the distance between the projection and the point at which the brake shoe is grasped guarantees minimum canting of the brake shoe and stable guidance in the groove, so that there is less likelihood of contact between the adhesive rear side of the brake shoe and the floating frame.